Colorado Frost Dates
Published: February 1, 2026 · Updated: April 23, 2026
Last Spring Frost
March 22
Zone 6b
First Fall Frost
November 10
Zone 6b
Frost-Free Season
233 days
Late March to Late November
Lawn Care Timing for Colorado
Vegetable Garden Timing for Colorado
Frost Dates by City in Colorado
Frequently Asked Questions
What is the last frost date in Colorado?
The average last spring frost in Colorado (zone 6b) is March 22. Dates vary by city and elevation. Find your specific city below for exact dates.
When is it safe to plant tomatoes in Colorado?
Transplant tomato seedlings outdoors after March 22 — the average last frost date for zone 6b. Start seeds indoors Early January. Wait 2 weeks after last frost for extra safety.
When should I overseed my lawn in Colorado?
The prime overseeding window in Colorado is September 1–October 15. This ensures 6 weeks of warm soil for germination before the first fall frost on November 10.
When should I apply winteriser in Colorado?
Apply winteriser fertiliser by Late November. Your first fall frost of November 10 is the hard deadline — apply at least 2–3 weeks before.
What USDA zone is Colorado?
Colorado contains USDA zones 6a, 6b. Each zone has different frost dates and growing seasons. Find your city below for your specific zone.